With the advance of digital technology, various digital products are used in the daily life, such as digital camera, or digital camera, PDA, MP3, industrial computer, and other customer applications, etc. These products are widely used and are designed well. However, since one may use various digital devices as required, and thus data are necessary to be transferred between these devices. Therefore, memory cards are developed to store data so that the data can be transferred between these devices. For various applications, the memory cards are designed with different types, such as compact flash cards (CD cards), smart media cards (SM cards), multi media cards (MMC cards), security digital cards (SD cards), memory stick cards (MS cards), magic gate cards (MG cards), micro drivers for transferring data and accessing devices. However, this induces an inconvenience for the customers. Moreover, different memory cards have problems of pin number and data formats. Thereby, this induces a problem about interfaces for converting data of different formats. As a result, the user still prepares various kinds of memory card adapter (for example, the interface card from converting memory stick card, see FIG. 8) to compact flash card for suiting different digital devices, and thus the cost is increased.